Hello, and welcome to Toyota Nation!
A great place for you to start is in the Common Problems, Solutions, And Questions For New Owners sticky thread, and under the
Commonly asked questions about the Highlander and its systems sub-section check out the various threads linked there that discuss beach and off-road use (located in the last link). You should find them interesting.
Edit: Here are a couple of links to recent threads about beach use as well:
Stuck in the sand today. Anything to do other than turning off VSC/Traction Control?
Off Road Capabilities on the Beach